JP2015-031226A discloses an internal combustion engine provided with a heat shielding film. The heat shielding film is formed on an aluminium-based wall surface that forms constitutes the combustion chamber. The heat shielding film includes an alumite layer and a sealing layer. The alumite layer is formed by anodization of the aluminim-based wall surface. The surface of the alumite layer has micro-pores which are formed during the anodization. The sealing layer is consisted of a sealing agent that seals inlets of the micro-pores. The sealing agent is polysilazane or polysiloxane.
The internal combustion engine is operated in various operation modes. The heavy use of certain operation modes (e.g., an intermittent operation during cold start, an idle operation) promotes generation of a deposit. When the deposit is generated on a wide area of the film surface, the action by the heat shielding film is inhibited. Therefore, in order to continuously exert the effect of heat shielding action, it is necessary to devise a method for suppressing the generation of the deposit on the film surface.
The present application addresses the above described problem, and one object of the present application is, to suppress the generation of deposits on the heat shielding film which is formed on the wall constituting combustion chamber in the internal combustion engine.